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United States Department of Agriculture

Agricultural Research Service

Title: Engineering New Crops for Safe Castor Oil Production

Authors
item Chen, Grace
item Ahn, Yeh Jin
item Vang, Louisa

Submitted to: Proceedings of Int'l Association of Plant Tissue Culture and Biotechnology
Publication Type: Proceedings
Publication Acceptance Date: November 15, 2006
Publication Date: August 15, 2007
Citation: Chen, G.Q., Ahn, Y., Vang, L. 2007. Engineering New Crops for Safe Castor Oil Production. Proceedings of Int'l Association of Plant Tissue Culture and Biotechnology.

Interpretive Summary: Castor plant (Ricinus communis L.) produces an unique seed oil with numerous industrial applications. However, castor seed contains the toxin ricin and hyper-allergenic 2S albumins detrimental to castor growers and processors. Our project goal is to develop a safe source of castor oil through genetic engineering. The general approach is to generate a safe castor crop by blocking expression of the ricin and 2S albumins in seeds. An alternative approach would be transgenic production of ricinoleate from temperate oilseed plants.

Technical Abstract: Castor (Ricinus communis L.) is an important oilseed crop with significant industrial value. Due to the presence of the ricin toxin and hyper-allergenic 2S albumins in seed, it is desirable to develop a safe castor crop. As part of a genetic approach to eliminate ricin and 2S albumins from castor, we have investigated endosperm morphogenesis and gene expression during seed development. We established a set of simple criteria, which included two visual markers, seed coat color and endosperm volume, and defined three phases that encompass the course of castor seed development. Our Northern analyses showed that the timing of the major expression of ricin and 2S albumin genes coincided with that of cellular endosperm differentiation. However, we observed different temporal expression patterns between ricin and 2S albumin genes. The ricin gene was up-regulated up to the last stage of cellular endosperm development, whereas the 2S albumin gene had a bell-shaped expression pattern. The different temporal expression patterns between ricin and 2S albumin genes indicate distinctive regulatory mechanisms involved in their mRNA accumulation. The results provide us with critical information to develop promoters and antisense constructs that would optimize timing of transgene expression to suppress the ricin and 2S albumins in a safe castor crop.

Last Modified: 10/31/2014
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